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Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
[6] A 20-cm thick wall of a house made of brick (k = 0.72W/m. C) is...
[6] A 20-cm thick wall of a house made of brick (k = 0.72W/m. C) is subjected to inside air at 22.C with a convection heat-transfer coefficient of 15 W/m2. C. The inner surface temperature of the wall is 18 C and the outside air temperature is -1 °C. Determine the outer surface temperature of the wall and the heat-transfer coefficient at the outer surface.
A thermocouple is used to measure the temperature of hot air flowing in a duct whose...
A thermocouple is used to measure the temperature of hot air flowing in a duct whose walls are maintained at Tw = 500 K. The thermocouple shows a temperature reading of Tt h = 850 K. Assuming the emissivity of the thermocouple junction to be 0.6, and the convection heat transfer coefficient to be 60 W/m2 · K, (a) draw the thermal resistance network, and (b) determine the actual temperature of the air.
Problem 3 (30): Steam at Too,1 340 °C flows in a cast iron pipe [k- 80 W/m.°C] whose inner and outer diameter are Di 6 cm and D2 -8 cm, respectively. The pipe is covered with a 4-cm thick glass wool...
Problem 3 (30): Steam at Too,1 340 °C flows in a cast iron pipe [k- 80 W/m.°C] whose inner and outer diameter are Di 6 cm and D2 -8 cm, respectively. The pipe is covered with a 4-cm thick glass wool insulation [k-0.05 W/ m°C]. Heat is lost to the surroundings at Too,2 - 21°C by natural convection and radiation, with a combined heat transfer coefficient of h- 18 W/m2 °C. Taking the heat transfer coefficient inside the pipe to...
3) A rectangular HVAC duct of cross-section 20 cm X 20 cm and 12 m long...
3) A rectangular HVAC duct of cross-section 20 cm X 20 cm and 12 m long is made of 3.5 mm thick sheet metal that is used to deliver hot air at 60°C with an average velocity of 4 m/s. The thermal resistance of the duct is negligible, and the outer surface of the duct, whose emissivity is 0.305, is exposed to the cold air at 10 C in the room, with a convection heat transfer coefficient of 10 W/m²....
A cylinder, 12 cm high and 8 cm in diameter, k = 12.5 W/mK, maintained at...
A cylinder, 12 cm high and 8 cm in diameter, k = 12.5 W/mK,
maintained at 36 ºC, is to be placed horizontally inside an
environment filled with air at 1 atm and 4 ºC. What is the
convection heat transfer rate between the cylinder and the air?
(Note: assume the cylinder is surrounded by air at 4 ºC, and
neglect heat transfer through the left and right end surfaces.)
A cylinder, 12 cm high and 8 cm in diameter,...
Part 2 - Problems (75 marks) I. Copper fins (k 401 W/mK) of uniform square cross-section...
Part 2 - Problems (75 marks) I. Copper fins (k 401 W/mK) of uniform square cross-section (2mm x 2mm) and length L 30mm are used in a fin array to enhance heat transfer from a 40mm x 40mm surface that is maintained at Tb 170°C. There are a total of 100 fins, and the tip of the fins is maintained at 35°C. Air circulates over the fin array with a temperature of To = 15°C and a convection coefficient of...
A water pipe from a house has a length of 0.5 m exposed to air atmosphere....
A water pipe from a house has a length of 0.5 m exposed to air atmosphere. If the duct is made of plastic (di=2 cm, do=2.4 cm, k=0.16 W/mK) and during the night the temperature is maintains at -5ºC for 14 h, with a combined transfer coefficient of heat by conduction and radiation of 40 W/m2K, calculate the mass of water contained in the tube that freezes overnight, considering that the tube contains water at 0ºC at rest (hfusion_water=333.7 kJ/kg).
The solar radiation incident on the outside surface of an aluminum shading device is 1300 W/m2...
The solar radiation incident on the outside surface of an aluminum shading device is 1300 W/m2 . Aluminum absorbs 10% of the incident solar energy, and dissipates it by convection from the back surface and by combined convection and radiation from the outside surface. The convection heat transfer coefficient is 10 W/m2 ·K for both surfaces, and the ambient/surrounding temperature can be taken 20 °C for both convection and radiation. Assuming that the aluminum shade has a uniform temperature, determine...
A 0.1 m thick brick wall with thermal conductivity 0.66 Wm K-1 is exposed to cold wind on the out...
A 0.1 m thick brick wall with thermal conductivity 0.66 Wm K-1 is exposed to cold wind on the outside of a house, at 270 K with convective heat transfer coefficient of 22.43 Wm2K1. On the inside of the house is calm air at 295.8 K, with a natural convective heat transfer coefficient of 10.49 Calculate the rate of heat transfer per unit area, in Wm, giving your answer to 3 decimal places
A 0.1 m thick brick wall with...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
[6] A 20-cm thick wall of a house made of brick (k = 0.72W/m. C) is subjected to inside air at 22.C with a convection heat-transfer coefficient of 15 W/m2. C. The inner surface temperature of the wall is 18 C and the outside air temperature is -1 °C. Determine the outer surface temperature of the wall and the heat-transfer coefficient at the outer surface.
Problem 3 (30): Steam at Too,1 340 °C flows in a cast iron pipe [k- 80 W/m.°C] whose inner and outer diameter are Di 6 cm and D2 -8 cm, respectively. The pipe is covered with a 4-cm thick glass wool insulation [k-0.05 W/ m°C]. Heat is lost to the surroundings at Too,2 - 21°C by natural convection and radiation, with a combined heat transfer coefficient of h- 18 W/m2 °C. Taking the heat transfer coefficient inside the pipe to...
3) A rectangular HVAC duct of cross-section 20 cm X 20 cm and 12 m long is made of 3.5 mm thick sheet metal that is used to deliver hot air at 60°C with an average velocity of 4 m/s. The thermal resistance of the duct is negligible, and the outer surface of the duct, whose emissivity is 0.305, is exposed to the cold air at 10 C in the room, with a convection heat transfer coefficient of 10 W/m²....
A cylinder, 12 cm high and 8 cm in diameter, k = 12.5 W/mK,
maintained at 36 ºC, is to be placed horizontally inside an
environment filled with air at 1 atm and 4 ºC. What is the
convection heat transfer rate between the cylinder and the air?
(Note: assume the cylinder is surrounded by air at 4 ºC, and
neglect heat transfer through the left and right end surfaces.)
A cylinder, 12 cm high and 8 cm in diameter,...
Part 2 - Problems (75 marks) I. Copper fins (k 401 W/mK) of uniform square cross-section (2mm x 2mm) and length L 30mm are used in a fin array to enhance heat transfer from a 40mm x 40mm surface that is maintained at Tb 170°C. There are a total of 100 fins, and the tip of the fins is maintained at 35°C. Air circulates over the fin array with a temperature of To = 15°C and a convection coefficient of...
A 0.1 m thick brick wall with thermal conductivity 0.66 Wm K-1 is exposed to cold wind on the outside of a house, at 270 K with convective heat transfer coefficient of 22.43 Wm2K1. On the inside of the house is calm air at 295.8 K, with a natural convective heat transfer coefficient of 10.49 Calculate the rate of heat transfer per unit area, in Wm, giving your answer to 3 decimal places
A 0.1 m thick brick wall with...
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